A roomba I was fixing had hair "growing" out of the brush gear box.
Opened it up & found one big hair ball. It looks like thier was origonally some lubricant about the consistancy of vasaline. After removing the hair what should I be putting in for lubrication & how much?

Also is it likely that the brush motor gears will be full of hair & need cleaning as well?

I used Silicone grease that I purchased from a hobby store. It is commonly used to lube radio control gearboxes that use plastic gears. Two roombas I repaired seemed a bit more quiet after I greased them.

I only use a small amount rather than filling the gearbox. Just enough to coat the teeth.

I just rebuilt my brush deck gearbox. The white lithium grease I had is dupont's white lithium grease with teflon. Bad idea! The lithium part is fine, however the teflon part is very viscous and leaks out the bottom of the gearbox. Eventually it will stop leaking, but in the meantime I have to put a towel under my roomba so it doesn't stain the floor.

Stick to the regular lithium grease, unless you want to put a diaper on your roomba!

Oh, gotcha. I am on my third Roomba in 4 years even with cleaning the gearbox. I bought it from Hammacher so it keeps going back with their lifetime warranty. Totally worth it! I'd be pissed if I only had a one year warranty for $400!